I was recently told by a friend, that using a laptop computer (while on your lap of course) will generate so much heat it will kill your sperm and make you infertile. Is this true?

Origins: Sometimes modern technology provides risks that aren't readily apparent, as appears to be the case with guys' using laptop computers balanced in their laps — in the process of reading their e-mails, checking on stock prices, and playing an online game or two, they may be reducing their reproductive chances.

A 2004 study from the State University of New York (SUNY) at Stony Brook involving 29 men (ranging in age from 21 to 35 years old) found that fellows who used laptop computers rested on their laps for an hour raised their scrotal temperatures by as much as 5°F. Since

other studies have demonstrated links between temperature increases and significant reductions in sperm production, the SUNY study concluded long-term use of laptops by teenage boys and men could be reproductively damaging. (According to the latter study, after a mere 20 minutes of laptop use the subjects experienced increases in scrotal temperatures sufficiently high to negatively affect the creation of sperm.)

The potential problems for men related to laptop use was deemed to be due not only to the heat generated by the machines, but also to the sitting positions employed by the users. "As well as being capable of producing direct local heat, [laptops] require the user to sit with his thighs close together to balance the machine, trapping the scrotum," explained Yefim Sheynkin, the researcher who led the study.

As to how serious the effect might be, the study noted: "We don't know the exact frequency and time of heat exposure capable of producing reversible or irreversible changes in spermatogenesis [the production of sperm]. Studies have shown significant but reversible changes after short-term heating. However, [laptop computers] produce significant repetitive transient scrotal hyperthermia for years, and insufficient recovery time between heat exposures may cause irreversible or partially reversible changes in male reproductive function."

Ergo, fellas, if fatherhood is in your plans, you might want to steady your laptops on tables rather than on your persons, at least until additional studies better identify the possible risks involved.